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Consolidated Quarterly Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Dec. 31, 2016	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment									$ 7,820	$ 15,896	$ 2,489
Severance benefit and charges	$ 1,800	$ 600	$ 800	$ 600					1,400
Impairment of fixed assets	1,100
Pension and post retirement net actuarial (gains) losses	(3,800)		(2,500)		$ (2,000)	$ 700	$ (700)	$ (1,200)
Restructuring and other
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment							1,400
Impairment of fixed assets and other expenses							4,200
Universal Robots
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment	$ 6,000	(300)	$ 1,500	600	$ 5,400	$ 8,000		$ 1,200	7,800	15,300	5,300
Universal Robots | Restructuring and other
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment							800
Avionics Interface Technologies, LLC
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment										600	$ (1,300)
Avionics Interface Technologies, LLC | Restructuring and other
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment							600
Wireless Test
Quarterly Financial Information [Line Items]
Lease impairment				$ 1,300
Wireless Test
Quarterly Financial Information [Line Items]
Lease impairment									1,000
Previously impaired lease termination		400
Impairment of fixed assets and expenses related to the Japan earthquake
Quarterly Financial Information [Line Items]
Property insurance recovery		5,100							5,100	5,100
Impairment of fixed assets and expenses related to the Japan earthquake | Restructuring and other
Quarterly Financial Information [Line Items]
Property insurance recovery							5,100
Impairment of fixed assets and expenses related to the Japan earthquake | Earthquake Related Expenses
Quarterly Financial Information [Line Items]
Impairment of fixed assets and other expenses		$ 800							$ 800	$ 900
Impairment of fixed assets and expenses related to the Japan earthquake | Earthquake Related Expenses | Restructuring and other
Quarterly Financial Information [Line Items]
Impairment of fixed assets and other expenses							$ 900

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Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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